Glowworm Fire Coals
The fire coals / pebbles only appear in appliances that lack a closed burner section. They serve 2 functions. The first is to allow the heat to be circulated to the room. The second function is safety, they are made to slot together in a specific way which aids complete combustion. If the coals or pebbles are assembled incorrectly, noxious gases could escape from the appliance due to incomplete combustion. Please read instructions for installation carefully or contact a registered gas safe engineer.